Galarian Farfetch'd

Galarian Farfetch'd is in a very awkward place. It shares the same DEX number and species with a regional Pokemon, yet it has not had any sort of regional restriction since its release. It's also unable to evolve currently, despite having an evolution in the main series that should be attainable in Pokemon Go for all intents and purposes. For now, it's best to try to catch a few good individuals when it's available (and some for PvP too!), and then forget about it until Sirfetch'd is released.... eventually.

Fury Cutter + Leaf Blade and Brave Bird or Brick Break

Fury Cutter doesn't get STAB, but its fast energy generation helps make use of its charge moves much sooner. Rock Smash is a pretty bad move even with STAB, and has pitiful energy gains. 

Leaf Blade the best charge move available, ties for the least amount of energy needed among the charge moves of Galarian Farfetch'd, and has a very high 2.0 DPE rating (Damage Per Energy). Brave Bird offers a good coverage option, though it's not the most impressive move in the game. Brick Break generally speaking is a very bad move due to its pathetic damage output, but the addition of STAB helps to make it less awful, and at the very least it can be spammed frequently.